Copper Releasing Research Articles

Cu-Al spinel oxide as a sustained release catalyst for methanol steam reforming: Enhancing the catalytic performance via surface reconstruction

Cu-Al spinel oxide as a sustained release catalyst gradually releases active metal Cu during the methanol steam reforming reaction, whose catalytic behavior depends strongly on the surface structure of the catalyst. In this context, Cu-Al spinel solid solution is synthesized by a solid phase ball milling method, followed by treating with acidic and basic solutions in order to modulate the surface composition and structure, thereby to further improve the catalytic performance. Nitric acid is effective for the removal of both surface dispersed Cu and Al oxide species, whereas sodium hydroxide is only effective for the removal of Al oxide species, and ammonium hydroxide shows the weakest effect, removing a very small amount of Cu and Al species. Accompanying with the loss of Cu and Al species, the catalyst surface undergoes structural reconstruction, showing a redistribution of Cu species. Consequently, the copper releasing behavior varies drastically. The catalytic testing results show that the nitric acid and ammonium hydroxide treated catalysts present improved activity, where in the former also shows better stability. Sodium hydroxide treatment has a negative effect on the sustained releasing catalytic performance. In combination with the characterization results of the tested catalysts, it is found that both the copper particle dimension and the microstructure strain of sustained released copper play important roles in the catalytic performance. The findings of this report provide a practical method for the improvement of the sustained releasing catalysis.

Surface Characteristics Together With Environmental Conditions Shape Marine Biofilm Dynamics in Coastal NW Mediterranean Locations

Microbial colonization of artificial substrates in coastal areas, which concerns hull ships, sensors as well as plastic debris, is of huge significance to attain a rational environmental management. Some surface and environmental drivers of biofilm development have previously been described but their relative impact on the formation of biofilms remains unknown while crucial. Especially, there is no evidence of the relative importance of physical surface properties (wettability, roughness, smoothness) compared to seawater characteristics in driving biofilm abundance and diversity. In addition, few studies have considered the temporal evolution of this complex form of colonization, which often prevent to globally understand the process. Using experimental facilities in two Mediterrranean locations, a multidisciplinary approach including surface characterizations as well as seawaterquality analyses, flow cytometry and 16S rDNA metabarcoding, allowed for the identification of the main drivers of colonization for two antifouling (AF) coatings. One AF coating released copper (SPC1) while the other limit colonization thanks to physical properties, namely a low surface energy, roughness and smoothness (FRC1). Results were obtained over 75 days and compared to a control surface (PVC). Biofilm development was observed on all surfaces, with increasing density from AF coatings to PVC. Pionneer bacteria were dissimilar within all three surface types, however, communities observed on FRC1 converged toward PVC ones overtime, whereas SPC1 communities remained highly specific. A remarkably low and unique diversity was found on SPC1 during the experiment as Alteromonas accounted for more than 90% of the community colonizing this substrate until 12 days, and remained one of the co-dominant taxa of mature biofilms. Moreover, clear differences were found between geographical locations. Low nutrients and higher hydrodymanics in Banyuls bay resulted in less dense biofilms overall compared to Toulon, but also in a the slower dynamic of biofilm formation. This is illustrated by the persistence of pioneer Alteromonas but also Hyphomonadacae after 75 days on SPC1. We concluded that, even if local environmental conditions influenced the composition of biofilm communities, particular physical features may control the biofilm density but not the diversity, while copper releasing coating controlled both. In addition, it is evident from these results that sequential biofilm dynamics should carefully be considered as initial processes of formation differed from the long-term ones.

Thermo-mechanical investigation of PEG–PVA biohybrid active film grafted with copper nanoparticles for packaging applications

The global fabrication of conventional plastics has increased attributes to the prodigious applications. The product developed in the present work is a vitreous alternative to the traditional, non-biodegradable, crude-based plastics, which degrades axiomatically. It compensates for the exceedingly depleting oil reserves and truncates the plastic waste. This research emphasizes the evolution of sustainable active food packaging film to proliferate the shelf life of a product and to retain the nutritional content. Here, copper nanoparticles are reinforced into the biohybrid film made up of using polyvinyl alcohol, polyethylene glycol and citric acid for an active copper releasing packaging system, which improves the barrier property of the film. Scanning electron microscopy micrographs of the copper nanoparticles and the reinforced films delineate the uniform distribution of the nanoparticles in the hybrid matrix. Biodegradation test examined the 16.69% for 1 phr copper-loaded film, which is high in contrary to others. The mechanical properties and heat stability of the biocomposite film meliorated significantly by the inclusion of 1% Cu nanoparticles. The water solubility of the nano-film ranges from 3.64 to 100%, depending upon the extent of crosslinking. The resultant hybrid film is versatile and can be utilized both as cured and uncured forms. The aforementioned properties make it pertinent for drug-delivery applications too.

Study of copper releasing rate from vinyl copolymer/Cu2O/Seanine 211‐based anti‐fouling paint coating

AbstractThe effects of Seanine 211 content rate on Cu releasing as well as coating properties were investigated. The process of releasing Cu has been studied in dynamic conditions with Seanine content of 0, 3, 5, 10 % and static conditions using Seanine content of 5 % (in weight). Under dynamic conditions, the Cu shall release at high speed in the first 2 days of the test, then remain stable and proportional to the time according to the linear‐line equation, maintained at ≈ 3.5 μg/cm2/day. Under static conditions, the process of Cu releasing is studied through the reduction of coating thickness, the results show that the coating abrasion rate is also proportional to the time and according to linear‐line equation. With the content of 20 % Cu2O (in proportion) and 5 % Seanine (in proportion), the coat has the following properties: relative hardness 0.5; impact resistance 65 Kg.cm; flexural strength 1 mm; adhesion cross cut at 1.

Cu1−xMgxAl3 spinel solid solution as a sustained release catalyst: One-pot green synthesis and catalytic performance in methanol steam reforming

A versatile and green method for the synthesis of an efficient catalyst applied in methanol steam reforming is promising in view of clean energy production. Cu1−xMgxAl3 ternary spinel oxide catalysts have been prepared by a one-pot solid-phase reaction method using Cu(OH)2, Al2O3·xH2O and MgCO3 as the raw materials. The structure, reducibility, surface chemical state, and the aluminum ion distribution are comprehensively characterized by XRD, UV–vis, XPS, H2-TPR, N2O chemisorption, and 27Al MAS NMR techniques. The performances of the catalysts in methanol steam reforming are evaluated. Compared with binary Cu-Al spinel, the incorporation of Mg into the spinel lattice results in the change of Al3+ cation distribution between tetrahedral and octahedral sites, and thus the variation of copper surrounding environment can be inferred. Consequently, the copper releasing rate from the Mg containing spinel structure declines substantially, which is believed to be in favor of maintaining a stable catalytic performance longer. Besides, the ternary spinel oxide might facilitate the in-situ formation of smaller nano copper metals compared to CuAl3 binary spinel catalyst. Among all the catalysts, Cu0.9Mg0.1Al3 presents the highest activity as well as the best catalytic stability. The findings of this report suggest that introducing a foreign cation into the Cu-Al spinel structure might be a promising way to regulate the copper releasing property for achieving a better sustained release catalyst system.

Enhancing effect of MgO modification of Cu–Al spinel oxide catalyst for methanol steam reforming

Cu–Al spinel oxide (CA) as a sustained release catalyst has been successfully used in methanol steam reforming and it is highly required to improve its catalytic performance. Here, surface modification of the CA with various MgO loadings was performed. Characterization results showed that MgO dopant had strong interaction with the CA, resulting in a substantial change of the surface microstructure. Importantly, a small portion of lattice Cu2+ was phased out while partial Mg2+ cations incorporated into the spinel structure, giving rise to a variation of the cation distribution. Consequently, the change of the Cu2+ surrounding environment made it become hard to be reducible, thus the doped catalysts showed a lower copper releasing rate and smaller copper particles. Then, the activity and stability were enhanced when a suitable amount of MgO was highly dispersed. Excess amount of crystalline MgO gave rise to easy coking that resulted in an inferior catalytic performance.

Copper release from copper nanoparticles in the presence of natural organic matter

Copper nanoparticles (CuNPs) are widely used and inevitably released into aqueous environments, causing ecological and health risks. Ubiquitous natural organic matter (NOM) might affect the copper release behaviors from CuNPs and their toxicity. This work aims to elucidate how NOM affects copper release from CuNPs, with a focus on the impacts of NOM properties and the NOM-CuNPs interaction mechanism. The copper release kinetics and different copper fractions induced by representative NOMs were characterized. The presence of NOM led to a more dispersive state of CuNPs clusters. Copper release mainly resulted from complexation reactions between CuNPs and functional groups of NOM. Humic substances were more effective in releasing copper than sodium alginate and bovine serum albumin, due to a higher amount of functional groups and lower molecular weight, which facilitated the contact and complexion reactions. Chlorination treatment of NOM significantly decelerated copper release due to the destruction of functional groups and less attachment of NOM. However, the copper releasing ability of humic acid was not substantially affected by Ca2+-induced coagulation. This study provides better understanding about the persistence and transformation of CuNPs in aquatic environments.

The Intrauterine Device in Women with Diabetes Mellitus Type I and II: A Systematic Review.

Background. Women with diabetes mellitus type I and type II need effective contraception for personal and medical reasons. Long acting reversible contraceptive (LARC) methods are among the most efficient and cost-effective methods. Study Design. We searched the Popline, PubMed, and clinicaltrials.gov databases from 1961 to March 2013 for studies on the efficacy of the IUD in diabetic women and the possible changes it may produce in laboratory parameters. Studies of at least 30 subjects with DM1 or DM2 who were studied for 6 to 12 months depending on the method of analysis were eligible. Results. The search produced seven articles which gave event rate efficacy evaluable results and three which evaluated the effect of the IUD on laboratory parameters. One of the earlier efficacy studies showed an abnormally high pregnancy rate which sparked a controversy which is discussed in the Introduction section. The remaining 6 studies produced acceptable pregnancy rates. The three laboratory studies showed that the copper and levonorgestrel releasing IUD/IUS do not affect the diabetic state in any way. Conclusions. The copper bearing and levonorgestrel releasing IUDs are safe and effective in women with diabetes type I and diabetes type II although the evidence in the latter is limited.

Microbial succession during a heap bioleaching cycle of low grade copper sulfides: Does this knowledge mean a real input for industrial process design and control?

The paper Bacterial succession in bioheap leaching ( Brierley, 2001) showed the search for methods to analyze the microbial dynamics in bioleaching industrial processes as a key challenge for advancing commercial bioheap applications. “Chemical and physical conditions within bioheaps change radically from the time the bioheap is stacked and inoculated until bioleaching is completed.” The results from a comprehensive monitoring program by culturing and molecular techniques in an industrial bioleaching process for run-of-mine (ROM) low grade copper sulfide ore in Chile is summarized. The analysis of the compiled information permits an understanding of changes in microbial substrates availability, chemical and physical conditions. A data mining technique, called decision trees was used to analyze the information and to establish rules that represent patterns in the data. The bacterial succession in bioheap leaching solutions allowed the leaching cycle stages to be described as: i) Acid conditioning and soluble copper releasing, ii) Chalcocite Bacterial leaching (ferrous oxidation); iii) Chalcocite Bacterial leaching (ferrous and reduced sulfur compounds — RISC oxidation); iv) Bacterial leaching of sulfide minerals with higher rest potentials (pyrite and covellite), and v) Bacterial oxidation of remnant sulfide minerals and RISC. The impact of other factors on microbiology, such as the solvent-extraction process, aspects of the industrial design and operation are also discussed.

Microbial Succession during a Heap Bioleaching Cycle of Low Grade Copper Sulphides. Does this Knowledge Mean a Real Input for Industrial Process Design and Control?

The paper “Bacterial succession in bioheap leaching” [1] initiated the search for methods to analyze the microbial dynamics in bioleaching industrial processes as a key to advancing commercial bioheap applications. “Chemical and physical conditions within bioheaps change radically from the time the bioheap is stacked and inoculated until bioleaching is completed.” The results from a comprehensive monitoring program by culturing and molecular techniques in an industrial bioleaching process for Run-of-mine (ROM) low grade copper sulfide ore in Chile will be summarized. The analysis of the compiled information permits an understanding of changes in microbial substrates availability, chemical and physical conditions. The impact of other aspects on microbiology, such as the mining programme and the industrial design are also considered. The bacterial succession in bioheap leaching solutions allowed the leaching cycle stages to be describe as: i) Acid conditioning and soluble copper releasing, ii) Chalcocite Bacterial leaching (ferrous oxidation); iii) Chalcocite Bacterial leaching (ferrous and reduced sulfur compounds –RSC- oxidation); iv) Bacterial leaching of sulphide minerals with higher rest potentials (pyrite and covellite ), v) Bacterial oxidation of remnant sulfide minerals and RSC.

Copper-release from yeast Cu(I)-metallothionein by nitric oxide (NO).

The reaction of yeast Cu-MT with nitric oxide (NO) was examined. A release of copper from the Cu(I)-thiolate clusters of the protein by this remarkably important reagent was observed in vitro. The characteristic spectroscopic signals of the Cu(I)-thiolate chromophores levelled off in the presence of a two-fold molar excess of NO expressed per equivalent of thionein-copper as monitored by UV-electronic absorption, circular dichroism and luminescence emission. At the same time all of the copper became EPR detectable. The oxidized metal ions could easily be removed from the protein moiety by gelfiltration. The reversibility of the copper releasing process is of special interest. The specific fluorescence and dichroic properties of the previously demetallized protein could be recovered up to 85% under reductive conditions. Moreover, no difference in the electrophoretic behaviour was seen compared to the untreated Cu-MT. Thus, NO may act as a potent metabolic source for the transient copper release from Cu-MT. In the course of an oxidative burst this highly Fenton active copper is able to improve the efficacy of biological defence mechanisms.

The intrauterine device, pelvic inflammatory disease, and infertility: the confusion between hypothesis and knowledge

An earlier editorial made many false claims against the IUD and women. In many cases, the author extrapolated experience from the Dalkon Shield to today's IUDs. He even said the modern contraception has not reduced fertility, but data from at least 7 developing countries clearly refute that statement. Moreover he claims that the most female ambition is motherhood. Thus he blamed women for high fertility rates without acknowledging that women in developing countries have little control over fertility. Husbands determine when and how often to have intercourse and whether to use contraceptives or not. Women do not always have access to contraceptives. The author boldly stated that the IUD poses a threat to future fertility because it causes pelvic infections. The real threat is intercourse by which upper genital tract infections are transmitted. It is these sexually transmitted diseases that cause pelvic infections. The studies the author quoted have been found to have considerable bias and/or methodologic flaws. Some studies used as the comparison group women using contraceptive which lower the pelvic infection risk. Contemporary studies find no increased risk of infertility in copper and hormone IUD users, but instead show increased risk for multiple sex partners. Some studies do indicate an increased risk shortly after insertion which is due to insertion instrumentation used. The author even claimed that a Swedish study concluded that IUDs promote pelvic infection in patients with gonorrhea and chlamydia. But the Swedish study found no difference in pelvic infection risk between IUD and non-IUD, nonhormonal contraceptive users. Based on hundreds of millions of woman-years of worldwide experience, WHO claims modern copper and hormone releasing IUDs, when used as directed, may be the most effective and reliable reversible contraceptive method. This editorial based on flawed conclusions and misinformation does an injustice to the IUD and to women.

Development of Human Embryos in the Presence of a Copper Intrauterine Device

This study was designed to examine the teratogenic potential of copper releasing intrauterine contraceptive devices on the developing embryo. The tissues and organs of 11 whole embryos between 7 and 12 weeks of gestation were histologically examined for copper absorption after exposure to a copper intrauterine device in utero. The findings were not significantly different when compared with a control group of 7 embryos. No malformation or copper aggregates were observed in the various organs and placentas. The observations in this small sample would suggest that the copper-releasing intrauterine device has no deleterious effects on fetal development. The question remains whether malformations reported in some cases are associated with copper deposits in the tissues or with free copper ions in the fetal circulation. The implications are discussed.

Two years of intrauterine contraception with levonorgestrel and with copper: A randomized comparison of the TCu 380Ag and levonorgestrel 20 mcg/day device

IUDs releasing 20 mcg/day of levonorgestrel (LNg20) were in randomized trial together with the Copper T, model TCu 380Ag, in seven centers involving 2244 women. Two-year (25 months) gross cumulative pregnancy rates were 0.2 ± 0.2 and 0.9 ± 0.3 for the levonorgestrel and copper releasing devices, respectively (P > 0.05). There were no ectopic pregnancies in more than 1600 woman-years of use of each device. Removal rates for bleeding and/or pain or for medical reasons other than menstrual problems did not differ significantly between devices. Oligomenorrhea or amenorrhea prompted 10.7 per hundred (gross rate, 8.4 net rate) women using the LNg 20 IUD to request removal in the two-year period, significantly above the 0.2 per hundred rate among women with the Copper IUD (P < 0.001). At the end of two years an estimated 59.4 per 100 women were continuing use of the LNg 20 IUD, and 67.5 per 100 (P < 0.001) with the TCu 380Ag. This difference is almost wholly ascribable to a marked reduction in bleeding episodes and days among women using the LNg 20 device with concomitant removal of device. Hemoglobin rose an average of 0.5g/dl (P < 0.001) for this group whereas women using the TCu 380Ag experienced a decline of 0.2g/dl compared with baseline values (P < 0.001).

The IUD After 20 Years: A Review

5 types of IUDs are currently available in the US: Lippes Loop Cu-7 Tcu 200 Progestasert and TCu 380A. Most prominent side effects to IUD use include bleeding and heavy menstrual blood loss expulsion of the device pain perforation and pelvic inflammatory disease. Although copper and hormone releasing devices have shown some improvement in effectiveness many of the same problems with side effects and complications persist. Experience in the past 2 decades has shown that IUDs appeal to some women and not to others and that it can be a safe and appropriate method for some women and not for others. It is particularly useful for women over the age of 30. The IUD has major benefits when compared with other methods of contraception. Successful IUD use demands active cooperation on the part of the user and provider.

A Statistical Evaluation of the Rate of Degradation of Copper Releasing IUCDs

A Statistical Evaluation of the Rate of Degradation of Copper Releasing IUCDs

Comparative glycolytic metabolism in the normal and in the copper treated human endometrium

Endometrial biopsies were taken from seven regularly menstruating women and from eleven different women wearers of an intrauterine device of the copper releasing type (Cu-T 200), first during the secretory half of the menstrual cycle (20 ± 1 day) and then in the same women during the proliferative phase (10 ± 1 day) of the next menstrual period. The untreated endometrium produced significantly more lactate during the secretory (2.6 ± 0.45 μmoles/mg DNA) than during the proliferative phase (1.62 ± 0.3). This tendency towards anaerobic glycolysis was also reflected in the observed decrease in oxygen uptake during the secretory phase. 14C-glucose conversion to 14C-glycogen was four times higher during the second half of the menstrual cycle (0.83 ± 0.16 μmoles of glucose converted/mg DNA hr −1 against 0.21 ± 0.05). During the proliferative phase, the presence of a copper IUD induced a significant decrease in the conversion of glucose to glycogen and to lactate and also a decrease in oxygen uptake and in the utilization of endogenous substrates. However, the conversion of glucose to 14CO 2 was significantly increased. The same pattern of changes was produced by the CU-T 200 during the luteal phase, but in this case the conversion of glucose to 14CO 2 was also significantly reduced.

The effect of incubating a copper releasing intrauterine device on sperm penetration and Spinnbarkeit of cervical mucus.

SummaryNormal mid‐cycle cervical mucus was incubated with a “opper Seven” intrauterine device for different periods of time and Spinnbarkeit, sperm penetration and copper levels were estimated. As the duration of incubation time increased, the Spinnbarkeit and sperm penetration decreased and the copper levels increased. Cervical mucus from women with “Copper Seven” intrauterine devices was also tested. The levels of copper producing inhibition of sperm penetration in vitro were much greater than those actually found in vivo. It was concluded that the contraceptive action of the “Copper Seven” intrauterine device is not primarilyachieved by its effect on sperm transport